The present invention is concerned with a method for feeding a growing substrate, such as peat, soil, compost, crushed mineral wool, perlite, vermiculite, or bark, by means of a feeding equipment into the cells of the set of growing cells placed underneath the equipment, whereat the feeding equipment consists of two horizontal feeding rolls, which are placed side by side and which are parallel to each other, pins of a resilient material, e.g. rubber or plastic, preferably polyurethane, being arranged as projecting from the roll faces, the pins projecting radially and being placed in the normal planes of the axes of the feeding rolls alternatingly in each feeding roll so that, in the space between the feeding rolls, the pins on the feeding rolls are placed as interlocking each other, and that the feeding rolls are rotated in opposite directions so that the roll faces directed towards each other have a downwardly oriented direction of rotation.
In the prior art, filling lines have followed two different filling methods. The most common method is the dosage of the filling material onto the cell system by allowing it to fall by the effect of the force of gravitation and compacting by vibrating the cell system and by compacting it from the top by means of various elements, such as brushes or pegs. With this method, in order that a good result could be obtained, a good filling material of uniform quality must be used and, in the case of cell systems of paper, the material must also be relatively dry (relative moisture content below 35%). Cell systems with thin and soft walls do not stand very vigorous compacting, and therefore their filling has been slow and often unsatisfactory.
A second prior-art filling line type operates so that the filling material is first compacted to an appropriate density, and it is coated with a suitable material, cut, and placed into the boxes. The method is slow and expensive, even though the filling result is good. This filling method also operates with less expensive filling materials of inferior quality.
The object of the present invention is to provide a feeding method with properties considerably more favourable than corresponding prior-art methods, and the method in accordance with the invention is mainly characterized in that the filling material of the cells, i.e. the growing substrate, is fed, preferably as moist, at a high speed into the cells by rotating the feeding rolls at a rotation speed of 500 to 1000 r.p.m.--the lower the specific weight of the filling material, the higher the speed of rotation--whereat the filling material is, by the effect of the circumferential velocity of the feeding rolls of about 3 to 10 m/s, rushed in the vertical direction into the cells of the growing cell system so that any filling material introduced into the cells earlier is compacted by means of the kinetic energy of the filling material, beginning from the bottom.
As advantages of the feeding method in accordance with the invention it should be mentioned that an inexpensive filling material is used, it has a high capacity, it does not cause dust problems, because moist filling material can be used therein. The filling material may also be relatively coarse, whereby macropores, which are important for the plants, remain in the cells. The degree of compacting of the feeding equipment is readily adjustable, and the constructional embodiment of the equipment is inexpensive and simple. The feeding equipment functions as a shredder of clodded filling material, but it does not grind the filling material to fine particles.